This invention relates generally to adhesive attachment assemblies or fixtures and related methods for securing an adhesive attachment or the like onto a supporting surface or substrate. More specifically, this invention relates to improvements in such adhesive attachment assemblies or fixtures particularly of the type described and claimed in commonly assigned U.S. Pat. Nos. 4,302,492; 4,338,151; and 4,390,576.
In many instances, it is necessary or desirable to attach an element such as a patch, threaded screw, or the like onto a supporting substrate. For example, it may be necessary to apply a thin patch to the skin of an aircraft or to the hull of a boat to repair a hole therein. Alternately, it may be desirable to mount a threaded screw or other device onto a substrate, for example, the windshield of an automobile, without requiring a hole to be made in the substrate. In many such cases, it is necessary for the attachment to be located on the substrate with relatively high precision and further that a positive force be applied urging the attachment against the substrate for at least some minimum time period to allow, for example, curing of an adhesive material to achieve a relatively secure bond with the substrate.
In the past, any different clamp and fixture devices have been proposed for use in temporarily holding an adhesive attachment on the surface of a substrate during the cure time of an adhesive material. The majority of such clamp and fixture devices have required some form of mechanical connection to the substrate by means of screws or other mechanical fasteners, clamping jaws, etc. However, these devices are not suited for use with extended surface areas or fragile or thin-walled substrates within which surface interruptions to accommodate mechanical fastening are not possible or are undesirable. Other fixturing devices have been proposed which rely upon suction cups for holding an attachment in position on a substrate, but suction cup devices are limited to use with relatively smooth-surfaced substrates and further function to retain the attachment in place without exerting significant positive forces urging the attachment against the substrate. As a result, with suction cup devices, the adhesive material on the substrate can be unevenly distributed and/or cure with less than optimum bonding strength.
Improved devices are described and claimed in commonly assigned U.S. Pat. Nos. 4,302,492; 4,338,151; and 4,390,576. More particularly, these patents disclose attachment devices having a support fixture for temporary securing to the substrate by means of a pressure-sensitive adhesive or the like and force-bias or spring means for applying a force urging an attachment into positive bearing engagement with the substrate. The support fixture or a component thereof is movable between a first position with the adhesive attachment substantially out of bearing engagement with the substrate to a second position with the attachment pressed against the substrate. An over-center type annular spring plate constitutes the movable component in most of the described embodiments.
While the improved attachment devices disclosed in the above-referenced patents offer significant advantages in comparison with the previous art, they have required several component parts which are manufactured separately and then assembled, resulting in a relatively costly product for some applications. Moreover, the orientation of the adhesive attachment during support fixture movement between the first and second positions has not always maintained or assured optimal flush contact with the substrate, resulting in occasional angular tipping or cocking of the attachment causing uneven distribution and curing of adhesive material. Still further in attachment devices utilizing a resilient foam pad as the biasing force mechanism, the foam pad has exhibited a tendency to degrade in specialized high temperature environmenss, for example, when the attachment device and substrate are autoclaved to cure a specialized adhesive material.
There exists, therefore, a significant need for an improved, relatively simple, and relatively cost-efficient adhesive attachment and fixture therefor, wherein the fixture can be formed substantially as a one-piece construction of molded plastic or the like, wherein the fixture includes means for orienting the attachment device during movement into engagement with a substrate, and wherein the fixture can withstand relatively high temperature environments. The present invention fulfills these needs and provides further related advantages.